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Home >> Ford >> 2000 >> Taurus LX, 3.0 2, AX4N >> Repair and Diagnosis >> External Pages >> Different car >> Section 1827 (Engine Controls - (Hybrid) - Pinpoint Tests DV - JD) >> PINPOINT TEST DW: Heated Oxygen Sensor (HO2S) >> Test Procedure

Test Procedure

WARNING: This page is about a different car, the 2007 Mercury Mariner and 2007 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
  1. DW1 DIAGNOSTIC TROUBLE CODES (DTCS) P0053, P0054, P0132, P0133, P0135, P0138, P0141, AND P1127: CHECK FOR SELF-TEST DTCS 
    • Are any of the following DTCs present during the PCM self-test: P0053, P0054, P0132, P0133, P0135, P0138, P0141, or P1127? 
    Yes No
    For DTCs P0053 or P0054, GO to  DW12.
    For DTCs P0132 or P0138, GO to  DW18.
    For DTC P0133, GO to  DW2.
    For DTCs P0135 or P0141, GO to  DW8.
    For DTC P1127, GO to  DW17.    		 For all others, GO toDIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS .
  2. DW2 CONTINUOUS MEMORY DTC P0133: CARRY OUT THE KOER SELF-TEST 
    • Engine at normal operating temperature.
    • Carry out the KOER self-test.
    • Is DTC P1127 present? 
    Yes No
    DISREGARD the current diagnostic trouble code (DTC) at this time. DIAGNOSE the next DTC. GO toDIAGNOSTIC TROUBLE CODE (DTC) CHARTS AND DESCRIPTIONS . GO to  DW3.
  3. DW3 CHECK THE HO2S RESPONSE TEST RESULTS 
    • Key ON, engine OFF.
    • Access the diagnostic monitoring test results for the HO2S11.
    • Is the indicated value greater than the minimum threshold? 
    Yes No
    CLEAR the DTCs.
    GO to  DW2.    		 GO to  DW4.
  4. DW4 CHECK FOR UNMETERED AIR LEAKS 
    NOTE: Fuel calculations can be affected by unmetered air leaks.
    • Carefully inspect the following areas for potential air leaks:
      • hoses connecting to the mass air flow (MAF) sensor assembly
      • hoses connecting to the throttle body
      • intake manifold gasket leaks
      • PCV disconnected.
      • the vacuum lines are disconnected
      • improperly seated engine oil dipstick, tube or oil fill cap
      • exhaust leaks at flanges and gaskets
    • Are any air leaks present? 
    Yes No
    REPAIR the source of the air leak. RESET the keep alive memory (KAM). REFER toRESETTING THE KEEP ALIVE MEMORY (KAM) . GO to  DW5.
  5. DW5 CHECK HO2S CIRCUIT CONTINUITY 
    NOTE: HO2S is displayed as O2S on the scan tool.
    • HO2S connector disconnected.
    • Check the connector (both halves) for any water contamination.
    • Connect a 5 amp fused jumper wire between the following:
      Point A HO2S Connector, Harness Side Point B HO2S Connector, Harness Side
      HO2S Signal VPWR
    • Key ON, engine running.
    • Access the PCM and monitor the HO2S Signal PID.
    • Is the voltage greater than 1 V? 
    Yes No
    INSTALL a new HO2S. REFER to ELECTRONIC ENGINE CONTROLS - HYBRID .
    CHANGE the engine oil and oil filter. RESET the keep alive memory (KAM). REFER toRESETTING THE KEEP ALIVE MEMORY (KAM) . REPEAT the self-test.    		 GO to  DW6.
  6. DW6 CHECK THE HO2S CIRCUIT(S) FOR AN OPEN IN THE HARNESS 
    NOTE: A vehicle hoist may be required to access the HO2S harness. Refer to JACKING AND LIFTING for the locations of the lifting points.
    • Key in OFF position.
    • Remove the jumper wire(s).
    • Visually inspect the HO2S harness for exposed wiring, water contamination, corrosion, and proper assembly.
    • PCM connector disconnected.
    • Measure the resistance between:
      ( + ) PCM Connector, Harness Side ( - ) HO2S Connector, Harness Side
      HO2S Signal HO2S Signal
      SIGRTN - Pin E41 SIGRTN
    • Are the resistances less than 5 ohms? 
    Yes No
    GO to  DW7. REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.
  7. DW7 CHECK THE HO2S CIRCUIT FOR A SHORT TO VPWR IN THE HARNESS 
    • Measure the resistance between:
      ( + ) PCM Connector, Harness Side ( - ) PCM Connector, Harness Side
      HO2S Signal VPWR - Pin B35
    • Is the resistance greater than 10K ohms? 
    Yes No
    GO to  DW8. GO to  DW10.
  8. DW8 DTCS P0135 OR P0141: CHECK FOR A SOURCE OF POTENTIAL HO2S CONTAMINATION 
    • Investigate the following items as potential sources of HO2S contamination:
      • use of unapproved silicon sealers
      • fuel contaminated by silicon additives
      • excessive oil burning (rings, valve seals, oil overfill)
      • glycol leaking internally in the engine
      • lead-contaminated fuel
      • short drive cycles in cold weather
      • use of unapproved cleaning agents
    • Is a concern present? 
    Yes No
    REPAIR the source of the contamination.
    CHANGE the engine oil and oil filter. RESET the keep alive memory (KAM). REFER toRESETTING THE KEEP ALIVE MEMORY (KAM) . REPEAT the self-test.    		 GO to  DW9.
  9. DW9 VISUALLY INSPECT THE HO2S HARNESS 
    • PCM connector connected.
    • Visually inspect the HO2S harness for exposed wiring, water contamination, corrosion, and proper assembly.
    • Is a concern present? 
    Yes No
    REPAIR as necessary.
    CLEAR the DTCs. REPEAT the self-test.    		 GO to  DW10.
  10. DW10 CHECK THE HO2S AND SIGRTN CIRCUITS FOR AN OPEN IN THE HARNESS 
    NOTE: Verify the harness pins are in the proper location.
    • Measure the resistance between:
      ( + ) PCM Connector, Harness Side ( - ) HO2S Connector, Harness Side
      HO2S Signal HO2S Signal
      SIGRTN - Pin E41 SIGRTN
    • Are the resistances less than 5 ohms? 
    Yes No
    GO to  DW11. REPAIR as necessary.
    CLEAR the DTCs. REPEAT the self-test.
  11. DW11 CARRY OUT THE KOEO ON DEMAND SELF-TEST 
    • Key ON, engine OFF.
    • Check for KOEO DTCs.
    • Are DTCs P0135 or P0141 present? 
    Yes No
    GO to  DW12. GO to  DW13.
  12. DW12 DTCS P0053 AND P0054: CHECK FOR VPWR IN THE HARNESS 
    NOTE: If DTCs P0053 or P0054 are present, test their related circuits individually.
    • Key in OFF position.
    • HO2S connector disconnected.
    • Key ON, engine OFF.
    • Measure the voltage between:
      ( + ) HO2S Connector, Harness Side ( - ) HO2S Connector, Harness Side
      VPWR SIGRTN
    • Is the voltage greater than 10 V? 
    Yes No
    GO to  DW13. REPAIR the open circuit. CHECK the fuses.
    CLEAR the DTCs. REPEAT the self-test.
  13. DW13 CHECK THE HO2S HEATER FOR SHORTS IN THE HARNESS 
    NOTE: If DTCs P0053 or P0054 are present, test their related circuits individually.
    • Key in OFF position.
    • HO2S connector disconnected.
    • PCM connector disconnected.
    • Measure the resistance between:
      ( + ) HO2S Connector, Harness Side ( - ) Vehicle Battery
      HO2S Heater Negative terminal
    • Measure the resistance between:
      ( + ) HO2S Connector, Harness Side ( - ) HO2S Connector, Harness Side
      HO2S Heater VPWR
      HO2S Heater SIGRTN
      HO2S Heater HO2S Signal
    • Are the resistances greater than 10K ohms? 
    Yes No
    GO to  DW14. REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test.
  14. DW14 CHECK THE HO2S HEATER CIRCUIT FOR AN OPEN IN THE HARNESS 
    • Measure the resistance between:
      ( + ) PCM Connector, Harness Side ( - ) HO2S Connector, Harness Side
      HO2S Heater HO2S Heater
    • Is the resistance less than 5 ohms? 
    Yes No
    GO to  DW15. REPAIR the open circuit. CLEAR the DTCs. REPEAT the self-test.
  15. DW15 CHECK THE INTERNAL RESISTANCE OF THE HO2S HEATER 
    • Measure the resistance between:
      ( + ) HO2S Connector, Component Side ( - ) HO2S Connector, Component Side
      HO2S Heater VPWR
    • Is the resistance between 3 - 30 ohms? 
    Yes No
    GO to  DW16. INSTALL a new HO2S. REFER to ELECTRONIC ENGINE CONTROLS - HYBRID . RESET the keep alive memory (KAM). REFER toRESETTING THE KEEP ALIVE MEMORY (KAM) . REPEAT the self-test.
  16. DW16 CHECK THE HO2S HEATER CIRCUIT FOR AN INTERNAL SHORT TO SIGRTN OR GND 
    • Measure the resistance between:
      ( + ) HO2S Connector, Component Side ( - ) HO2S Connector, Component Side
      HO2S Heater SIGRTN
    • Measure the resistance between:
      ( + ) HO2S Connector, Component Side ( - ) Vehicle Battery
      HO2S Heater Negative terminal
    • Is the resistance greater than 10K ohms? 
    Yes No
    GO to  DW23. INSTALL a new HO2S. REFER to ELECTRONIC ENGINE CONTROLS - HYBRID . RESET the keep alive memory (KAM). REFER toRESETTING THE KEEP ALIVE MEMORY (KAM) .
  17. DW17 KOER DTC P1127: EXHAUST TEMPERATURE OUT OF RANGE 
    NOTE: Address all other DTCs before proceeding.
    • Key ON, engine running.
    • Engine at normal operating temperature.
    • Access the PCM and monitor the HO2S Heater PID.
    • Is the PID state ON? 
    Yes No
    CARRY OUT the KOER self-test. RUN the engine until the PID indicates ON. CARRY OUT the KOER self-test.
  18. DW18 DTCS P0132 AND P0138: VISUALLY INSPECT THE SUSPECT HO2S HARNESS 
    NOTE: Only the suspect HO2S needs to be diagnosed.
    • Key in OFF position.
    • HO2S connector disconnected.
    • Visually inspect the HO2S harness.
      • Check the connector (both halves) for any water contamination.
      • Make sure the connector pins are fully seated.
    • Is a concern present? 
    Yes No
    REPAIR as necessary.
    CLEAR the DTCs. REPEAT the self-test.    		 GO to  DW19.
  19. DW19 CHECK THE SUSPECT HO2S SIGNAL LEVEL TOO HIGH 
    • HO2S connector connected.
    • Key ON, engine running.
    • Access the PCM and monitor the HO2S Signal PID.
    • Is the voltage less than 1.1 V? 
    Yes No
    GO to  DW20. GO to  DW21.
  20. DW20 CARRY OUT A THOROUGH WIGGLE TEST ON THE SUSPECT HO2S HARNESS 
    • Key in OFF position.
    • Key ON, engine OFF.
    • Access the PCM and monitor the HO2S Signal PID.
    • Carry out a thorough wiggle test on the HO2S harness.
    • Does the voltage change during the wiggle test? 
    Yes No
    REPAIR as necessary.
    CLEAR the DTCs. REPEAT the self-test.    		 refer to PINPOINT TEST Z .
  21. DW21 CHECK THE SUSPECT HO2S SIGNAL FOR A SHORT TO VPWR INSIDE THE SENSOR 
    • Key in OFF position.
    • HO2S connector disconnected.
    • Key ON, engine running.
    • Access the PCM and monitor the HO2S Signal PID.
    • Is the voltage less than 1.1 V? 
    Yes No
    INSTALL a new HO2S. REFER to ELECTRONIC ENGINE CONTROLS - HYBRID . RESET the keep alive memory (KAM). REFER toRESETTING THE KEEP ALIVE MEMORY (KAM) . REPEAT the self-test. GO to  DW22.
  22. DW22 CHECK THE SUSPECT HO2S CIRCUIT FOR A SHORT TO VPWR IN THE HARNESS 
    • Key in OFF position.
    • PCM connector disconnected.
    • Key ON, engine OFF.
    • Measure the voltage between:
      ( + ) HO2S Connector, Harness Side ( - )
      HO2S Signal Ground
    • Is any voltage present? 
    Yes No
    REPAIR the short circuit. CLEAR the DTCs. REPEAT the self-test. GO to  DW23.
  23. DW23 CHECK FOR CORRECT PCM OPERATION 
    • Disconnect all the PCM connectors.
    • Visually inspect for:
      • pushed out pins
      • corrosion
    • Connect all the PCM connectors and make sure they seat correctly.
    • Carry out the PCM self-test and verify the concern is still present.
    • Is the concern still present? 
    Yes No
    INSTALL a new PCM. REFER toFLASH ELECTRICALLY ERASABLE PROGRAMMABLE READ ONLY MEMORY (EEPROM) . The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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